Translucid antislipping tile



- nan-Bo s'r p PANY, or wonons'rna, mnssacnusrz'rrs, A conronerron ermessncnusnrrs. i rmmstuein an'rrsmrrme man a citizen ofthe United.States of America,

. slippery and frequently cause accidents to residing. at Worcester, inthe county of Worcester and Stateof Massachusetts, have invented certainnew and useful Improvements in Translucid Antislipping Tiles, of

which the following is a full, clear, and exact specification.

lvfy' 'nvention relates to safetytreads and more particularly totranslucid tlles, having hard, wearresisting, granular materialincorporated therein and designed especially for illuminating. vaultcovers and generally for preventing slipping of pedestrians on any treadsurface.

lnthe larger cities it is customary for business houses to have rooms orpassages projecting from'the buildings beneath the sidewalk or pavement,and to provide tread surfaces for the sidewalk which permlt the passageof light therethrough. The construction ordinarily involved is that of ametal frameworkv carrying. glass bodies fixed therein, but it is foundthat these glass bodies and their supporting frames are verypedestrians.

Numerous attempts have been made to provide non-slip vault covers orilluminat:

ing-tread surfaces by makingthe frame supporting the glass tiles of amaterial intended to prevent slipping thereon. 'lhe frame constructionsheretofore provlded have proven inefficient, mainly because they soonbecome slippery after a short period of wear. -lhe glasses haveordinarily been left with all. their slippery features intact, althoughit has been proposed to provlde rooves in the surface of a glass plateand ill them with cement, vitreous material or metal to preventslipping. -This latter scheme is obviously impracticable since thecement, etc., is not intimately bound to the glass and ma easily bedislodgedfrom the grooves by tile shocks of pedestrian wear, and'suchmaterials in. themselves have no lar e wearing and anti-slippingqualltles an are entirely unserviceable for such purposes. Hencetheseproposed schemes have never been put to extendedlpractical use andpedestriansstill try to avold walking over glass vault lights.

It has also been proposed to make safety stair and platform treads ofvitrified ceramic Speeiilcation of Letters Eatent, ApplicationflledAugust 3, 1918. Serial 33 0. teases.

anti slipping Patented Apr. 5, 1%21.

material having anti-slipping granules incorporated therein. The processniceramic manufacture involves theelaborate opera; tlons of mixing thevarious ingredients together w1th water to the right de greeofplasticlty, shaping the product as desired and then burning the body ina 'ln at a high temperature for a long perio of time and subse uentlyallowing'it to cool for a similarly ong time.

quires considerable skilled labor, especially r This process is obvously'slow, tedious and expensive and re neuros s-anemones, orwoacrs'rrn, massacnusrrrs, essxeuoe-ro roa'ron couin the firing orburning of the material."

Safety tiles are becoming of increasing importance for use not only asvault lights but also in public thoroughfares, station platforms,stalr-treads and other localities where there is danger of a pedestrianslipping on the tread surface and falling or becoming injured thereby.These blocks must be made, therefore, in large quantities; and in orderthat they may be utilized freely the process of manufacture should becheapened as much as possible and it should be feasible to produce thetile rapidly and with the minlmum amountof skilled labor involved.

It has furthermore been found that the ceramic tiles do not possess acompact, dense structure but ordinarily have large pores and so areperv1ous to water, Hence moisture is absorbed by any tiles which areexposed to climatic and other-like conditions and they become unsanitaryand are dificult to clean.

It is accordingly an object of my invention to provide a translucid bodyhaving anti-slipping granular material incorporated therein, which maybe utilized to conduct light and yet serve as. a flooring or treadsurface and moreparticularly as a vault light glass for sidewalks.

A further object of my invention is to provide a safety tread .tile of acompact,

dense structure which is impervious to moisture and ma be kept sanitaryand clean, which is hig 1y resistant to footwear and which possesseslarge anti-slipping qualities and is of general utility for walksurfaces.

A still. further object is to utilize the simple rocesses of glassmanufacture and there y to provide a safety tread or antislipping tilebody which may be cheaply,

easily and quickly manufactured, which may be cast ormolded to anydesired shape an does-not require prolonged heat treatment thereafterbut may be made by the simple process of fusing certain materialstogether, incorporating therewith hard, wear-resisting, antisslippinggranules. .and thereafter shaping the tile body as desired from thefused materiaL. i

' With these and other objects in view, as will be apparent from thefollowing disclosure, myinvention resides in the combination ofingredients and the composition of a tile body as set forth in thespecification and covered. by the claims appended hereto.

I have found that translucid or light-conducting bodies for use insidewalk vault lights and other lighting surfaces adapted to be exposedto considerable pedestrianfoot-wear maybe suitably made by incorporatinga hard, wear-resistin anti-slipping, granular material in a used glassysilicate body in intimate relation with the constituents of the, glass.For the antireferably utilize a granular substance WhlCll has a hardnessof nine or more on Mohs scale and which has high frictional or abradingqualities as well as great durability and wear-resistingcharacteristics. I find that silicon 'carbid and crystalline alumina arebest adapted for this purpose and I preferably use the latter. Thecrystalline alumina may be either the natural emery or corundum or anartificial product comprising the chemical aluminum oxid combmed withmore or less of various impurities. The artificial alumina may be made,for example, by fusing bauxite in-an electric furnace. The resultingoxid, etc.

product contains a large percentage of crystalline alumina intermingledwith various impurities such as silica, titania, iron The quantity andnature of the hard, wear-resisting, non-slip material may obviously bevarled, depending upon the char acteristics needed for any particularlocality. For some uses I prefer to employ a large proportion of theanti-slipping ma-' terial with the glass, but .for ordinary purposes itis sufiicient that the granules be rom fifteen to forty percent. of thetotal j mass. The size of the granules depends upon the permitted amountof abrasive action upon foot-gear, but I find that a grain passingthrough a 36-mesh sieve will prevent slipping and yet not cause materialwear on the shoe leather. Furthermore, these granules may be locatedonly in the .top layer or surface of the block or that portion which isadapted to be exposed to the foot-wear.v

In order that my invention may be more A satisfactory tile may be madeof a sodaat will by askilled glass manufacturer withthe scope of hisknowledge of glass makmg and t e claims covering my invention.

lime-magnesia glass .of the following proportions: Ma esi a M O) 6.4parts b weight. Wh iting M60 16.0 Soda ash (Na CO 72.1 Glass sand (SiO186.0 Crystalline alumina $6 a r (t The process of manufacture mayinvolve well known steps in the glass-making and working industry. Forexample, I may mix the glass ingredients together and introduce theminto a suitable lass furnace in small batches until the desired has beenfused. The temperature 0 the reaction is so regulated that the silicamay be able to unite with the calcium, magnesium and sodium and form aglass which is prob ably a compound silicate of these metals. Duringthis reaction there is considerable 8 uantlty frothing, due to theevolution of carbon di-g oxid as bubbles, and various means or methodsshould be adopted to eliminate the rwidu'al bubbles in the glass, as forexample by super-heating the'mass after the if materials have been fusedand allowing the bubbles to work off gradually. Foreign bodies or otherimpurities present on the surface of the mass may be removed byskimming.

Since there is a tendency for the fused i silicates to unite withalumina, I prefer to incorporate the crystalline alumina granules, ifsuch are used, with the mass after the fusion and formation erably 'ustbefore casting or molding the tiles. 5 4 e viscosity of the melt israisedconsiderably by the addition of alumina, hence it ma be advisableto maintain the high heat 0 fusion and not permit the material to coolto any large extent before molding, as is customary in the plate glassindustry. This feature, however, depends upon the accompanyingconditions of manufacture. The granular material maybe mixed with theglass by a olin operation or anyother suitable methos, an while it is insuspension or uniformly distributed throu hout the glass the mixture isoured into t e molds and shaped as desire The tiles are preferablyshaped by being forced into contact with the 'mold by means of' plungersworked by air or steam pressure.

If the granular material is to be incorporated only in the surfaceof theblock it may be sprinkled on the surface of the fused glass in the moldand forced into the mass y pressure. This may also be accomplished ofthe glass and prefby making two lass batches, one containing the granues an the other not, and form in two layers thereof in the mold. Ifdesirecfi glass previously cast may be melted to suflicient plasticityto allow the incorporation therewith of the anti-slipping material.Various other methods readily suggest themselves to one skilled in thisart and may obviously be utilized in the practice of my invention.

In this-way I may form a translucid tile or body adapted to be usedwhere excessive foot-wear occurs, and which will prevent slippingthereon. If the translucid properties of the tile are not desired theymay be modified,'disguised or removed, as by making the glass colored,frosted or opaque or to present any desired surface or optical proerties. The tile may be shaped'as desire but I prefer to use rectangulargeometrical patterns in a floor and so make the tile as"parallelepipedons. The anti-slipping glass body may be formed inirregular plastic flooring or otherwise suitably sha e desire to secureby Letresisting, anti-slipping, granular material.

incorporated in its upper surface layer by fusion of the glass forexposure to pedes- 40 trian foot-wear. Y

3. A safet .lucid body aving granular material incorgranules.

shapes for use as terrazzo chips in a setting 7 antitread tilecomprising a transand large anti-slipping 5. A safety tread tilecomprisin a dense, non-porous lassy silicate body aving a crystallineumina material incorporated therein.

6. An anti-slipping tile comprising a body 65 of glass having intimatelyincorporated therein a quantity of crystalline alumina 7. A safet treadtile comprising a body of non-ar '1 aceous glass having intimatelydistribute throughout its volume a quantity of granules which have ahardness of nine or more and are adapted to be exposed on the surface ofthe tile, as the latter wears away, and prevent a pedestrian slippingthereon.

8. A safety tread comprising adense, non

' porous and translucent glass body, the surace portion of which hasatleast 15% by weight of hard, wear-resisting, anti-slipping 70 granulesfused therein.

9. A safety tread comprising a dense, nonabsorbent, glass bod containingfrom 15% to 40% by Weight 0 crystalline material of a hardness of 9- ormore intimately incor- 75 porated therein.

10.,A safety tread comprising a dense, non-absorbent, glass bodycontaining from 15% to 40% by weight of crystalline aluniinaincorporated therein by fusion of the ass. g Signed at Worcester,Massachusetts, this first day of Au st, 1918.

' EEILTON F. BEEOHER.

